The present invention relates to dispensers for flexible strand materials. In particular, the present invention relates to cassettes that deliver modeling material in the form of continuous filaments to a modeling machine for building three-dimensional objects.
Extrusion-based layered manufacturing machines build three-dimensional objects or models by extruding solidifiable modeling material from extrusion heads in predetermined patterns, based upon design data provided from computer aided design (CAD) systems. One technique for supplying modeling material to an extrusion head is in the form of a filament strand. The modeling material is then extruded layer-by-layer in areas defined from the CAD model. The material being extruded fuses to previously deposited material and solidifies to form a three-dimensional object resembling the CAD model.
One technique for supplying modeling material to a three-dimensional modeling machine includes providing modeling filament in an enclosed cassette. The cassette contains spooled filament which is advanced to the machine through an exit orifice of the cassette. The cassette can be made air tight and sealed so that the filament can be kept in a dry environment. As many modeling materials are moisture sensitive (e.g. high-temperature thermoplastics), maintaining dryness of the filament is desirable for building accurate, robust models. However the problem with this delivery system is that the spool can rotate inside of the cassette during transport and handling. This inadvertent rotation may cause the filament to unravel, which may result in tangling or breakage. In such a case, the cassette may fail to properly deliver filament to a modeling machine. As such, it is desirable to maintain a sealed cassette while increasing the reliability of filament to modeling machines.